Description
In the very early chapters - like the quick tour and installation - we want to gently introduce the idea of unzipping Symfony into a web-accessible path, and then accessing it like "http://localhost/Symfony/web/app_dev.php". We ultimately want to tell people to change their document root, so that in the rest of the documentation we can simply say "app_dev.php/hello/Fabien".
Right now (see #2100), I think we can do a better job with this. We need to re-read the Installation book chapter and the Quick tour to make sure we're introducing this idea properly and consistently so that if, for example, you followed the quick tour and/or the installation chapter, then started reading another chapter, your code will work (i.e. we haven't skipped explaining any necessary steps).